This invention relates to a vessel occlusion system, and particularly to a system for delivering an embolus through a catheter or the like into a vessel situated in a body to occlude or close the vessel. More particularly, this invention relates to a method and apparatus for moving an embolus through an introducer catheter inserted through a venotomy into a body to reach a destination in a blood vessel or the like and occlude the vessel during a surgical procedure.
Embolization is a procedure used by surgeons to block fluid flow through a blood vessel or organ. Typically, a mass of material called an embolus is inserted into a body using a catheter and lodged in a blood vessel or organ to provide an obstruction therein. Lodging an embolus in a blood vessel obstructs blood flow through the vessel and causes a thrombus or blood clot to develop in the vessel. The thrombus remains attached to the embolus and blood vessel wall at its place of origin to plug the vessel and obstruct blood or other fluid flow therethrough.
Embolization is used, for example, for therapeutic purposes to reduce blood loss during hemorrhage or treatment of unresectable lesions or to permit preoperative control of blood flow. Embolization of feeding vessels is known to reduce bleeding during surgery. For example, it is used in surgery prior to resection of vascular tumors.
Many types of emboli are known. For example, coils made of spring wire, sponges made of absorbable gelatin or other chemical cross-linking means such as cyanoacrylate or the like, detachable balloons, umbrella-like devices, and other types of plugs are used to embolize a vessel. Any device which has thrombotic properties when placed in a vessel having a proper internal diameter and does not cause significant foreign body reaction can be used to embolize a vessel to occlude the vessel totally or partially.
A guide wire can be used to load an embolus into an introducer catheter or to discharge an embolus from its place in an introducer catheter into a vessel or both. A guide wire sized to pass through the lumen of the introducer catheter can be used to move an embolus into and out of an introducer catheter as long as the surgeon has the necessary skill and expertise.
One object of the present invention is to provide a method of hydraulically delivering a vessel-occluding embolus into and through a catheter to each blood vessel branching out from a trunk-like vein during a surgical procedure.
According to the present invention, a method is provided of passing an embolus into and through the lumen of a catheter to reach a destination outside of the catheter in a vessel. Initially, the catheter is inserted through a venotomy into a body and guided therein to aim the outlet of the catheter into the selected vessel. An embolus is positioned outside of the catheter in a hollow cartridge coupled to the lumen of the catheter at its inlet. A stream of pressurized fluid is then conducted through the hollow cartridge to discharge the embolus from the cartridge into the lumen of the catheter and propel the embolus through the lumen so that the embolus exits at the outlet of the catheter and reaches the destination in the vessel. The fluid used to flush the embolus into and through the catheter is water or another biologically compatible fluid such as saline.
In preferred embodiments, the positioning step includes the steps of providing a hollow cartridge formed to include a passageway therein containing the embolus and coupling the hollow cartridge to the catheter at the inlet to place the passageway and the lumen in communication to permit movement of the embolus therebetween through the inlet of the catheter. The conducting step further includes the steps of providing a supply of fluid and pressurizing a predetermined volume of fluid from the supply at a predetermined rate to generate the stream of pressurized fluid. For example, it has been observed that only 0.5-3 cubic centimeters of fluid are needed to deliver an embolus to a target site in a collateral blood vessel using the method of the present invention.
The embolus is preferably a normally coiled spring that has been straightened to a somewhat linear shape to assume an "uncoiled" configuration for containment in the cylindrical passageway formed in the cartridge. The tendency for the uncoiled spring to reconfigure itself to its coiled configuration causes the spring (embolus) to exert a predetermined force against an interior wall defining the passageway to retain the spring (embolus) temporarily in an initial position within the cartridge passageway. Advantageously, the stream of pressurized fluid is used to apply a predetermined amount of work to the embolus to overcome frictional forces between the embolus and the interior wall of the cartridge passageway to dislodge the embolus from its place in the hollow cartridge so that it can be moved by the stream of pressurized fluid into and through the catheter to reach its destination in the vessel.
Illustratively, the catheter used to deliver the embolus to the target site is guided through various body passageways to reach the target site by means of a second catheter having a lumen sized to receive the embolus-delivery catheter therein. The second catheter is preferably steerable and aimable by remote control to guide the embolus-delivery catheter extending therethrough to the mouth of the selected blood vessel or organ containing the target site.
Advantageously, the method and apparatus of the present invention permit a surgeon to embolize one or more vessels or organs in a body without using a guide wire to push an embolus into or through an embolus-delivery catheter to reach the target site in the body. An embolus-delivery catheter is sometimes called an "introducer" catheter. Further, use of a stream of pressurized fluid to move am embolus from a hollow cartridge into and through an introducer catheter provides an embolus delivery system that is easily manageable by the surgeon during embolization. Such a hydraulic system offers many advantages in use because it operates to cause a uniform, predetermined force to be applied to an embolus on command during each embolization.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.